Introduction
Restoration of sagittal balance is often a key goal in Lumbar Interbody Fusion (LIF). Here, we test whether there is a correlation between pain (e.g. musculature pain,
degenerative pain) and sagittal balance. We aim to 1) use clinical x-rays to 2) take radiographic measurements of Segmental Lordosis (SL) and global Lumbar Lordosis (LL), and test whether these relate to clinical outcomes.
Methods
Clinical and radiographic data were collected from a multi-center, multi-surgeon, postmarket study of anterior lumbar Patient Specific Implants (PSI). Clinical outcomes included VAS and EQ-5D (QoL) scores, while radiographic outcomes included SL and LL measurements from sagittal Xrays.
Results
We report radiographic and clinical outcomes for a cohort of 49 patients (66 operated levels). Although SL increased significantly for the operated level, overall LL (L1-S1) often increased by less, or in some cases decreased.
VAS and QoL scores improved significantly from pre-operative means of 8.0 (1.5 SD) to 2.4 (2.2 SD), and 0.30 (0.34 SD) to 0.78 (0.22 SD) with a mean follow up time point of 19 months.
Discussion
Multiple studies (Smith 2023, Ashgar 2024, Kent 2024) have highlighted the potential for surgeons to more reliably achieve their pre-operative alignment goals with PSI compared to off-the-shelf devices.
On average in our cohort, global lordosis increased by 4.6° less than SL (SD=8.1). Compensatory mechanisms may be responsible for the high variability in changes between SL and LL. As the target level is restored, other levels may ‘relax’, suggesting the importance of defining patient specific segmental targets.
Regression analysis was performed to test for significance between clinical outcome (VAS and QoL), radiographic outcome and patient demographics. Clinical outcomes were not correlated with LL or SL results, and as SL was not directly related to LL, the relationships between SL, LL and clinical outcomes are complex and non-predictive.